Fuel tank filler gauge



FIG. 1 is a top, front, and right side perspective view of a fuel tank filler gauge showing my new design;

FIG. 2 is a front elevational view, the rear elevational view being identical;

FIG. 3 is a right side elevational view, the left side elevational view being identical; and

FIG. 4 is a top plan view, the bottom plan view being identical thereof. 

The ornamental design for fuel tank filler gauge, as shown and described. 